Two-cycle internal-combustion engine



A. G. L. AND H. c. w. NElGHBouR.

TWO-CYCLE INTERNAL QMBUSTION ENGINE.

' APPLlcATloN FILE/D 1uLY2s,1918

sans@ ara amara e. L.. amenacen AND naam e.

W. nnrclaecua, oa'amearon, vvrcfroma,

AUSTRALIA.

TWO-CYCLE INTERNAL-COMBUSTION EGINE.

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" I Application led Jul-y 23,v

has been previously compressed either in the engine crank case or by an auxiliary pump, is transferred to the working cylinder so as to give smooth entrv thereto without throttling; means whereby the intermingling of the incoming charge with the exhaust gases is reduced and means whereby a free exit for the latter is provided with improvedv scavenging of the cylinder.

A further object of the invention is to obtain a more certain firing of weak mixtures and improved running at low speeds.

The invention, moreover, provides remov- 1 able means for readily obtaining access to the inlet and exhaust ports to vfacilitate the removal of carbon deposit therefrom.

rlhe essential features of 'the invention comprise a piston, the head of which is made conical in shape and has formed therein a passage extending from a port at the side of said piston to a central hole at the top of said conical head, the incoming charge being adapted to pass through the passage to the said central hole and being thereby axially directed to the top of the engine cylinder.

. Furthermore, the invention provides a cylinder head so shaped that when the entering charge impinge's centrally thereon it is smoothly directed outwardly around said cylinder-head an-d is then turned downwardly and inwardly into the cylinder,A driving before it the burnt gases which strike upon the sides of the conical piston head and are therebydiverted outwardly through an ex-. haust port of ample area.

In internal combustion engines of this type, as ordinarily constructed, thel piston towards the end of the power stroke uncovers a port in the cylinder wall through which Specification of ,Letters Patent.

- haust -port as possible.

Patente-dg may 25, i922. 1918. Serial No. 246,289.

the exhaust gases escape. :Shortly after'- wards and just prior to the piston reaching theJi end of the power stroke it uncovers a secon usua cylinder so as to'lie as far away from the ex- The explosive charge which has been compressed in the crank case by the piston during the power stroke, .or has been compressed by an auxlliary pump, passes through the transfer port into the cylinder. The enterlng charge partly Idrives out the remaining exhaust gases.

. To reduce mixing of /the entering charge with kthe exhaust gases, the piston is' provided with a defiector situated adjacent to the said transfer port. The said deiiector, which is made in a variety of shapes of greater .or less efficiency, directs the incoming charge upthe side of -the cylinder towards the top. The piston then rises up compressing the charge, which is fired at the end of tne stroke in the ordinary way.

ln the present invention the same cycle of operations is followed, but the parts .are so constructed and arranged that a free and unimpeded entry and circulation of the enterin charge to the cylinder is obtained which port, termed the transfer port which is I 1y situated on the opposite side of the "lo h e ectively scavenges the same, increases the readily understood reference will now be had to the accompanying explanatory drawings, wherein l Figure 1 is a view in vertical section of a two-cycle engine, wherein the piston is shewn at the end of the power stroke.

`Figure 2 is a similar view to Figure l and wherein the piston is shewn at the end of the compression stroke.

Figure 3 is a view in transverse section through the exhaust port taken on the line 3 3 in Figure l. p

Figure 4 is a view in perspective of the piston. l

. Figure 5 is a fragmentary view in vertical section of the door for cleaning the piston passage and is drawn to a larger scale.

, Figure 6 is 'a face in Figure 5.

Figure 7 is a fragmentary view in vertical section shewng the cylinder head fitted with heated-tube ignition.

Fi re 8 is a similar view to Figure 7 i shewing the cylinder head fitted with heatedence denote the same o r correspendin in the different views and the numera 1 designates the cylinder of a two-cycle internall chamber or` automatic ignition.

In these drawings like characters of referparts combustion engine wherein a piston 2 4is adapted to reciprocate. The head 3 of this piston 2 is made conical in shape and is provided at its apex with a central circular hole 4. This hole 4 is connected' by a passage in the iston head to an openlng or port 6, prefera ly rectanglular in shape, in the side of the iston 2. he passage 5 is made to gradua ly change in shape from the rectangular port 6 to the circular hole 4 as indi-v cated ,by broken lines in Figure 4. l

. Shortly before the end of the downward or power stroke of said piston 2 the portA 6 therein uncovers the ransfer port 7 inthe side of the cylinder 1 which is connected by a transfer .passage 8 formed in the wall of the said cylinder 1 with the crank case 9, or

.with an auxiliary pump (not shewn) when the latter is employed. Said transfer port 7 and transfer passage 8 are likewise of rec- 'tanilar shape to conform with the shape of t e piston port 6. n Y. At the end of the power. stroke of the pisi ton 2 the ports 6 and 7 are in exact align:

ment, and the pistonpassage 5 and the transfer passage. 8 combine to form a smoothly curved continuous u ward passage having a bend therein of amp e radius.

The explosive mixture which has been compressed in the crank case 3 by the downward stroke of the piston 2, or by an aux-v iliary pump, passes upwardly throughthis contlnuous passage and is thereby smoothly directed without'choking or throttling from the crank case 9 to the apex of the conical piston head 3.

The entering charge in consequence issues with high velocity from the aforesaid central circular hole 4 and is axially projected to -the top of the c linder 1 in the form of a divergent conica jet as indicated by arrows in Figure .1.

The passage 5 can be made of vuniform area from end to end thereof, or it can be gradually constricted more or less 1 in area towards the central hole 4, thereby permitting the velocity of the said conical jet to be increased to a desired extent.

The cylinder head 10 is provided with a central downwardly depressed conical boss 11, andthe walls of the cylinder head 10 surrounding said boss 11 are curved outwardly and downwardly to the part of the cylinder head 10 of maximum internal diameter.

The maximum internal diameter of the 'maaar cylinder head 10 'fis preferably' somewhat greater than the diameter of the said cylinder 1,;which makes the latter easier to bore in manufacture, and the walls lof said cylinder head 10 below the part thereof having the greatest internal diameter are inclined inwardly and downwardly to meet the upper end of thecylinder 1.l I

The conical jet after'axiall ascending the cylinder 1 impinges upon said central conical boss 11 and the incomin mixture is thereby smoothly directed on al sides around the cylinder head 10 and by the latter is again directed downwardly and projected inwardlyinto the cylinder 1, as shewn by arrows in Figure 1.

Thefdescending charge displaces the burnt gases downwardly and the latter strike upon the sides ofthe conical piston head 3 and are thereby deflected laterally through the exhaust port 12 which has been opened a little in advance of the transfer port 7 by the upper edge of the piston 2 which forms the base of the conical piston head 3.

The high volocity of the central conical jet, which has a free and unimpeded circulation in the cylinder 1 combined with the curved shapeof the cylinder head 10 prof duces whirlingl or turbulence of the charge in the combustion; chamber 13 which experiment has shewn to be necessary to ensure -of the cylinder 1 in a thin stream.

The conical piston head can be made with conical sides as indicated by the broken v'lines in Figure 4, but the sides thereof are preferably made to curve downwardly/and outwardly, as shewn. By being so constructed they more eiciently turn aside the descending burnt gases through the exhaust port.

The exhaust port consists of a series of openings 12 made around the cylinderl with their top edges lying in a plane at right angles thereto so that all of said openin 12 are simultaneously opened and closed by the piston 2 as'it reciprocates. The openings 12 extend for a considerable distance around the cylinder 1 but not so far as to lie in the path of the port 6 pf the piston 2 as the latter reciprocates. -Said openings 12 can be made parallelly-to the axis of the cyl- I' around a cylinder forming an exhaust port aeeaeee both sides ofthe central one are also curved in a horizontal plane for this purpose as shewn Figure 3. c We are aware that a rmg of openings is old and well known andno for-such arrangement. c

The openings 12 lcommumca-te with ka claim is made hinge' pintles 29 which rest `nrecessee 3Q formed in the sides of said opening 26.

In order to fix the upper end of said door 28 in position there are formed on the outer side thereof lugs 31`in which a pin 32 is detachably fitted, the ends of said pin normally resting in recesses 33 formed in-the sides of said opening 26.

In operation, the cover 27 is removed and the door 28 is opened outwardly tol permit the p-in 32 to be Withdrawn laterallyl from said lugs 31. The door 28 is then pushed groove 14 extending a required distane\ inwardlyvtolrest upon the inner wall of the around theoutside of the cylinder 1 and lying between radially-projecting flanges integrally formed with said cylinder 1. The

of. the water Aures 1 and 2.

vertical ribs 17 formed integrally with and connecting the flan es. 15 and it is' provided upper of said flanges 15 formsthe'bottom jacket 16 as is shewn in 'Fig- The groove 14 is closed iat its ends by witha cover 18 to 'orm an exhaust chamber 19. Saidcover 18 isso constructed that the exhaust chamber 19 gradually converges into a circular outlet 200i:l ample area, and

, it is furnished with a flange 21 to which the,

exhaust pipe (not shewn) is attached.

In two-cycle.v engines .of small size the lexhaust port is` apt to become more or less choked by carbonl deposit, which must be removed from time to time, and it is therefore desirable that access be readily obtainable to said port; For this purpose 'recesses 22 are formed around the flangesl into which the cover 18 is fitted. Internally projecting s lugs 23 formed near the ends of the cover f 18 are provided with studs 24 which extend through holes in said ribs 17 and are fitted with nuts 25. v Upon removal of these nuts 25 the cover 18 can be easily taken ofi' i laterally in the direction of the arrow in Figure 3 thereby giving ready access to the openings 12 for cleaning purpo the`- cover 18 is. replaced the nuts 25 are tightened up to firmly x said coverl 18 again in position. If desired, suitable packing (not shewn)- can be inserted between the -edgesof the cover 18 and-the inner end of said recesses 22.

In order to .obtain access to the piston passage 5 for cleaning purposes an opening 26 formed in the wall of the transfer passage 8 is'normally closed by -a'gas-tight cover 27 which can be removed whenever it is desired to clean said passage 5;

It is important when removing carbon deposit that the latter should be prevented from falling through the transfer passage 8 into the crank case 9 and in order to provide for this a hinged door 28 is located within said opening 26. The inner side of this door 28 conforms to the shape of the passage 8 and said door l28 is pro-vided with ses. When over, provide convenient access to theports 6 and 7 and the openings 12 during manu-- facture, allowing said ports and openings to be accurately adjusted as by tiling, and enabling perfect timing of the transfer and exhaust operations to be easily obtained.

When the explosive mixture is compressed in the crank case 9 prior to its transference to the cylinder 1 it is drawn into said crank case 9 by the vacuum produced therein by the ascent of the piston 2, either through a port 34 which is uncovered by the piston at the end of the compression stroke as in F igure 2 or through an automatically or mechanically operated valve'in said crank case 9. These devices are well known and form npart of the present invention. The port 34 is shewn directly beneath the exhaust outlet 20 for convenience of illustration, but

said port 34 can be located at some other preferred part of the circumference` lof cylinder 1 as will be readily understood.

The slopin sides of the piston head 3 combined wit openings 12 enable a very free exhaust to be obtained'. This is most essential in this form of engine as the dwell of the piston at the end of the power stroke beingof very brief duration it is of the utmost importance that the pressure in the cylinder should rapidly fall to that of the atmosphere in order to provide sufficient time for the entering charge to displace the residua-l gases and eliciently scavenge the cylinder.

ing effect. v

der resulting in a decrease of the volumetric4 efficiency of the engine. 4

The transfer port 7 is not uncovered by the piston 2 in the usual way, but commumcates with the interior of the cylinder 1 by way of the passage 5 in the piston head 3, as hereinbefore described, and the said transfer port 7 lies further down the cylinder 1 than the exhaust port. v

One or more piston packing rings 35 is or are arranged between the upper edge of said piston 2 and the portl 6 therein.- At the end of the power stroke of the piston 2 and during the period of exhaust of the burnt gases and entry of fresh explosive.

charge the piston ring or rings 35 is or are situated between the said transfer `and exhaust ports, as shewn in Figure 1, thereby `preventing leakage from the former to the latter port.

Owing to the disposition of the portsv 6 and 7 and the passage 5 and the exhaust openings 12 `the entering charge is enabledy to drive out the residual gases as Vabove described, thereby obtaining `an approximately end to end scavenging of the cylinder 1 without added complications of extra passages, valves,' and other parts.

The transfer passage 8, piston passage 5- and exhaust openings 12'can all be made of ample area to allow their functions to be rapidly performed and thereby permit an increase of piston speed with corresponding increase in the length of stroke.

The top of-the said conical piston head 3 lies at some distance above the base thereof, so that while the transfer of 'the fresh charge from the crank case 2 or auxiliary? pumping cylinder (not shewn) to the engine cylinder 1 is taking place the 4riskof intermingling with the residual burnt gases,

and the escape of entering charge through 'the exhaust openings 12 is greatly reduced,

especially as the said charge is centrally directed to the top of the engine cylinder 1.

The 'conical piston head 3 is far easier to machine than the piston head provided with a deiectr, and it may be turned and polished without dificulty.

Inpractice, it is found that carbon will not deposit readily on smooth polished surfaces. Consequently the deposition of carbon on the piston head 3 which is apt to occur 'in two-cycle engines may thereby be largely obviated, especially as the sloping sides of the piston head 3 are,i swept by a.

downward rush of the escaping exhaust,

gases.

When the piston 2 reaches the end of the for industrial purposes.

anatre' When electric ignition is employed the sparking plug 36 1s screwed lcentrally intok the boss 11 and the spark gap 37 is located A so lthat l"it enters the aforesaid hole the apex of the piston head 3.

When a tube 38 heatedby a burner 39,

tat

or achamber 40 which is initially externally heated and thereafter maintained at a high temperature by the heat of the explosions is used as a source of ignition the orificev 41'leading therefrom passes centrally through the boss 11 and the lower end thereof is likewiseadapted to enter-the hole 4 at the apex of the piston head 3. These forms of 1 ition are old and well known and in themse ves form no part of the invention.

The said central hole`4 at the apex of the piston .head 3 and the passage 5 leading thereto contain explosive mixture which cannot become diluted with burnt gases, and whenA the piston 2 reaches the end of the compression stroke, the -said contained mixture is brought directly into contact with the source of ignition. l i

Firing 4of the charge is `thereby greatly facilitated and rendered more certain, improving the ,operation of the engine at slow speeds or when using weak mixtures, the effect of Athe .dilution ofthe chargek by burnt gases being then more pronounced. Owing `to the location of the means of Iignition as abovel described,'the com ressed It will be obvious to persons skilled in the art that the ordinary simple type of two` cycle internal combustion engine arranged l and vconstructed according to the present invention will be thereby improved in operation and rendered more eiicient without in anv way addingl to its complexity and cost.

The two-cycle engine above described and illustrated-in the drawings is of the marine type, `but the same construction can be employed in two-cycle engines -for motor vehicles, or in stationary two-cycle engines Moreover the invention can be applied to engines having horizontal or inclined cylinders, or cylinders disposed in other preferred positions.

Explosive mixture has been described as if passing into the cylinder 1 from the piston passage 5, but air alone may similarly enter the cylinder l to scavenge it, the fuel being injected under pressure through a jet 42 at the end of the compression stroke in the ordinary Way, as will be readily understood.

What we do claim is:-

1; A two-cycle engine comprisinga cyl* inder, a conical boss projecting inwardly and axially from the cylinder and ignition means in said conical boss, an annular combustion chamber of curved cross-section centrally .disposed around said conical boss and having a maximum diameter greater than the cylinder diameter, the annular Wall of the combustion chamber being inclined inwardly to the cylinder Wall, a transfer port and a transfer passage` in' the wall of the cylinder, an annular series of exhaust openings in said cylinder wall, a hinged door and a detachable gas-tight cover permitting access to said transfer passage, va detachable casing enclosing said exhaust openings, an exhaust outlet in said detachable casing', a piston in said cylinder, a conical extension on said piston, a port at the side of said piston, a central hole in the apex of said conical extension, a passage connecting the said hole and the `said port, and one or more packing rings in the piston between the exhaust openings and the transfer port when the piston is at the end of its power stroke, substantially as described.-

2. In a two-cycle engine, a cylinder, a transfer passage in said cylinder, a transfer port at the end of said transfer passage, an exhaust port in said cylinder arranged 'bppositely to said transfer port, an annular combustion chamber of curved cross section at the end of said cylinder, said combustion chamber having a maximum diameter greater than the cylinder diameter and having a sloping wall inclined inwardly to the cylinder wall,

. a conical boss projecting inwardly and axially into said combustion chamber, a piston in said cylinder having a conical head, a

port in the side of the `piston, an opening at the apex of the conical head, an inlet passage in said conical head connecting said opening with the port in said piston, and ignition means in said boss arranged so as to project into said opening at the endof the compression stroke, substantially as described.

3. lin a two-cycle engine, a cylinder, initial compressing means, a transfer passagie in said cylinder connecting the latter with said initial compressing means, a transfer port in the cylinderwall at the end of the transfer passage, a series of exhaust openings i'n said cylinder arranged oppositively to s'aid transfer port, a conical boss projecting inwardly and axially from the cylinder end, ignition means -in said boss, an. annular com- 'bustion chamber of curved cross section centrally disposed around said boss and having a maximum diameter greater than the diameter of said cylinder, a piston in said cylinder, an inlet passage forming an initial combustion chamber in said piston, and a port in the side of th piston at the end of the inlet passage, said inlet passage and said transfer passage being arranged to form a Vcontinuous upwardly curved passage at the end of the power stroke, and said exhaust openings being situated so as not to be in the path of the port in the-side of said piston, substantially as described.

4. In a two-cycle engine, a cylinder, a

conical boss projecting inwardly and axially from the cylinder end, ignition means in said conical boss, an annular combustion chamber of curved cross-section centrally disposed around said conical boss and having a maximum diameter greater than the cylinder diameter, the annular wall of the com-y bustion chamber being inclined kinwardly to the cylinder Wall, substantially as described. l 5. In a two-cycle engine, a cylinder, a transfer port and a transfer passage in the wall of said cylinder, an annular series of exhaust openings in the wall of said cylinder, a hinged door and a detachable gas-tight cover permitting access 'to the said transfer passage, a detachable casing enclosing the said exhaust openings, and an exhaust outlet in said detachable casing, substantially as described.

6. In a two-cycle engine, a cylinder, a transfer passage in said cylinder, an opening in the outer wall of said transfer passage, a door in said opening, hinge pintles on said door, lugs on the outer side of said door, a pin in said lugs and recesses in the opposite sides of said opening for said hinge pintles and the' ends of said pin and a gas-tight detachable cover on said opening, substantially as described.

7. In a two-cycle engine, a cylinder, an exhaust port in said cylinder, flanges extending partly around said cylinder, a groove between said ilanges, ribs formed at the ends of saidgroove, a detachable cover fitting said recess, internally projecting lugs formed on said cover, studs in sald lugs passing through holes in said ribs, 'nuts on said studs, an opening in said cover and a flange around said opening, substantially as described,

In testimony whereof we aiiix our signatures in presence of two witnesses.

ARTHUR G. L. NEIGHBOUR. HARRY C. W. NEIGHBOUR.

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